STRATIGRAPHIC CORRELATION OF A PRE-ILLINOIAN DIAMICTON, NORTHWESTERN MISSOURI

This paper reports ongoing investigations in the Quaternary record of northwest Missouri. Abers (1991) defined the Independence Formation, type section in northeast Kansas, based on the criterion that preglacial chert gravel, quartzite, granite, and other Canadian Shield erratics are present in diamicton and interbeded stratified sediments. A stratigraphic column was measured and lithologies in the diamicton were identified, using hand sample, grain mount, and x-ray diffraction analyses methods. The study site is located just north of Barnard, MO, in Nodaway County on an upland. Therefore, the thickness of the diamicton is hypothesized to be minimal compared to its occurrence in nearby buried valleys. The total stratigraphic thickness of Quaternary sediments exposed in the Barnard Quarry was 9.1m to 15m. Thickness of the weathered diamicton ranged from 2 to 3 m and was overlain by highly oxidized sediments composed of red and yellow clays (30% percent by volume) and capped by a silty-clay loam soil. The diamicton contained chert nodules, quartzite, granite, and other igneous and metamorphic Canadian Shield erratics. Granitic boulders were so highly weathered that they occurred as ghosts and when handled, broke down to form a quartz-sand and clay noncohesive unit. Other erratics from the Canadian Shield include: gabbro, basalt, rhyolite, diorite, gneiss, and greenstone. Local bedrock consists of Pennsylvanian shale and limestone; however, carbonate minerals have been leached from the diamicton. Preliminary results indicate that a brown, clay-rich stony diamicton in Nodaway County, MO, is correlative to the upper diamicton of the Independence Formation, the type section of which is south of our study location. The lowermost diamicton of the Independence Formation is absent at this locality. Correlation with Independence Formation places the age of the brown, clay-rich stony diamicton at 0.7 to 0.6 million years BP, which corresponds to oxygen-isotope stages 18-16.